Connecting tubes of the type defined above are generally attached to fluid headers of small transverse dimensions, and in particular to tubular fluid headers such as those used in condensers. Such connecting tubes generally have a circular cylindrical body, and they are usually attached to circular cylindrical fluid headers, the diameter of which is similar to that of the body of the connecting tube.
By flattening the end portion of the connecting tube so as to give it a generally oblong shape, fitting of the tube into an oblong aperture formed in the wall of the fluid header is facilitated, while some latitude is afforded in the choice of location and orientation of the connecting tube in relation to the fluid header.
In known connecting tubes of this type, the deformation of the end portion, in order to flatten it, is carried out in a progressive manner starting with the cylindrical body, which also creates a transition zone (or intermediate deformation zone) in which the wall of the connecting tube defines a rounded shoulder. This is the case, in particular, in the heat exchanger disclosed in the specification of French published patent application FR 2 249 299A, although the fluid header and the connecting tube of that heat exchanger may be made of a plastics material, which is not the case in the present invention.
As a result, in the above mentioned transition zone, the connecting tube cannot preserve such a high resistance to fluid pressure as in the actual body of the tube itself. In addition, the transition zone increases the height or length of the connecting tube, due to the fact that its cylindrical body is necessarily attached at a certain distance from the wall of the fluid header, and this depends on the radius of curvature of the rounded shoulder.